"We" are people in charge of setting policy for schools. Why would you prefer they ignore a problem rather than take precautions when it turns out to not be a problem? It seems that the costs of your error is higher than the costs of my error.

"Better that ten guilty persons escape than that one innocent suffer."

Though I'd argue that any n - ten, one hundred, ten billion - is better to let escape.

It was pointed out recently that the words "essential" and "temporary" are often left out, which quite changes the meaning (although I think it's really one of degree, whether or not Mr. Franklin agrees with me). You left them in, which I appreciate, so I'll just ask this question: Is locking the classroom doors until a problem is resolved (what happened here) giving up an "essential liberty" in exchange for a little temporary safety?

The student was arrested without cause. I'd definitely say that his essential liberty was sacrificed.

(Not to mention anybody who was detained because of the lockdown - be they visiting adults or students who were scheduled to leave the property for whatever reason.)